The most important function of a pediatric intensive care unit (PICU) is to provide advanced computerized monitoring capabilities to clinicians to evaluate the clinical status of patients and to track their response to a wide range of interventions. We hypothesize that integrating and analyzing multiple, clinically important variables as: a. real time continuous physiologic monitoring parameters (i.e. temperature, heart rate, blood pressure, central venous pressure, pulsed oximetry, and end tidal carbon dioxide concentrations); b. with established indices of pediatric mortality (power prectral analysis of heart rate variability); c. coupled with intermittent, physiologic based measures of organ function, many known to predict mortality from PRISM III (arterial blood gases, serum organ specific enzyme levels, etc); and d. known demographic predictors of mortality from PRISM III will create a real time, continuous, integrated, composite index of risk for impending mortality and/or instability (REALTROMINS - Real Time Risk of Mortality and INStability) in critically ill children using advanced signal processing, statistical, data fusion and mining techniques. With the accomplishment of these goals, new, advanced critical care monitoring technology will have emerged that will provide real time continuous assessment of A) the level of critical illness in these children and B) the efficacy of a multitude of medical interventions, that will help return critically ill children back to health.